This invention relates to product labelling.
Products to be sold are commonly labelled. In this regard, automatic labelling apparatus may be employed where the products are smaller and processed in large volumes. One approach in this regard is to wipe a label onto each product as its passes a labelling head. This approach, however, is only well suited for labelling products of uniform dimensions. Where products have irregular dimensions, such as agricultural produce, the distance between a given product and the labelling head will vary. To label such products, tamping labellers are typically used. U.S. Pat. No. 6,257,294 to Weisbeck discloses a tamping labeller. In Weisbeck, a turret carries a number of reciprocating pick up heads about its periphery. The turret has a vacuum plenum and a positive pressure plenum. The turret rotates each head, consecutively, to a labelling station. A head normally communicates with the vacuum plenum which keeps it in a retracted position; also, due to end perforations in the head, the negative pressure holds a label at the end of the head. However, when the head reaches the labelling station, it is coupled to the positive pressure plenum which causes the head to rapidly extend until it tamps a product below. The force of the tamping forms an adhesive bond between the pressure sensitive adhesive of the label and the product. Labels are fed to each pick-up head from a label cassette with a label web comprising serially arranged labels on a release tape.
The labelling apparatus of Weisbeck is suited to label a continuous line of products passing under the labeller. However, more typically, agricultural produce which is to be labelled arrives in trays, each tray having an arrangement of cup-like depressions which hold the products. In order to label products in a tray, a bank of tamping labellers may be used and the trays conveyed underneath this bank of labellers. However, with this set-up, some mechanism is required to ensure that the labellers, when tamping, do not miss the products. One approach in this regard is to use a limited number of types of trays to hold the products, where each type of tray has a pre-defined pattern of cup-like depressions. The labelling apparatus may then be configured to expect products to be arranged in a certain pattern, with the expected pattern being based on the type of tray that will next pass under the labellers. With such a system, a vision system may be used to detect the type of tray.
A drawback with this approach is that products may not be present in each of the tray cups. A further drawback is that some types of products, such as vine ripened tomatoes, may have obstructions (the vines) which may end up being labelled rather than the product itself.
Therefore, there remains a need for more accurate product labelling apparatus.